This invention relates to sheet metal building construction and, in particular, to a roof support system for use in a structure using sheet metal framing members.
As evidenced by the roof systems disclosed in U.S. Pat. Nos. 3,952,461 and 2,272,910, most buildings utilizing sheet metal construction abandon the traditional roof type system involving the use of rafters and purlins in favor of single piece roof sections. In this type of construction, support for the roof is provided by reinforcing ribs that are adapted to coact with the roof comb. Although the single piece roof arrangement has proven to work quite well in practice, it nevertheless requires that each of the interlocking pieces that make up the individual roof sections be precisely fabricated so that they come together properly in assembly without bending or otherwise deforming the parts. To precisely form the parts requires special tooling which is not only expensive but also difficult to maintain within working tolerances. As a consequence, the cost of the component parts is high and the scrap rate is also high. Similarly, because supporting truss and purlins are not used, the amount of roof area covered by the sections is also restricted.
Most buildings utilizing specially designed sheet metal roof sections are generally modular units which afford little or no flexibility of design. Accordingly, many buildings employing sheet metal construction tend to be box-like structures having relatively little if any aesthetic value. For this reason architects and designers have generally avoided using sheet metal roof systems in their structures.